UK Prime Minister Tony Blair is to visit his Italian counterpart Silvio Berlusconi as Italy remains on high alert after a terror attack threat.

The deadline for Italy to withdraw its 3,000 troops from Iraq, set by a group linked to al-Qaeda, expired on Sunday.

The Abu-Hafs al-Masri Brigades posted a statement on an Islamic website saying the Italian government had "dug its own grave" by ignoring the demand.

Mr Blair and his family are due to stay at Mr Berlusconi's Sardinian villa.

The Italian visit is the latest leg of Mr Blair's summer holiday which has included a trip to Barbados and the opening of the Olympic Games in Greece.

Calm

It is still unclear who exactly is behind the Italian threat as there have been a number of claims and counter claims in the name of the Brigades.

The Abu Hafs al-Masri Brigades has previously issued threats against European countries for not responding to a "truce" issued to them by the al-Qaeda leader Osama bin Laden, which expired in July.

The group also claimed responsibility for the Madrid train bombings in March.

But as the latest threat deadline expired on Sunday, Italy's Interior Minister Giuseppe Pisanu said Italians were reacting calmly to the threats.

"The Italians aren't changing their habits and thus they respond, in the most composed manner, to the relentless campaign of media statements... which aim to amplify the threat of Islamic terrorism," he said.

AFP news agency says some 13,000 potential Italian targets are now permanently guarded by 23,000 police and soldiers, between 5,000 and 6,000 of them in Rome.